Subsoil irrigation combined with an impermeable layer has been known for a long time (for example by the trade name Hydrak). It is a method the essential feature of which is that an artificial, impermeable webbing is placed about 60 cm below the ground surface, at the depth of the root zone of the plants, and irrigation pipe is laid above the impermeable layer. With that process, the root zone of the plants is kept adequately moist even in soils with poor water retention, according to a program, without loss by evaporation and seepage, during the whole growth season. This produces high yield on barren, otherwise non-yielding terrain, independently from precipitation conditions. The root zone of the plants can be continuously supplied with dissolved plant protective agents and nutrients incorporated in the irrigating water, at a low cost while also protecting the environment.
A large scale use of that process was not possible so far due to the fact, that no means was available for the economical realization thereof.
Some experiments have been performed for the construction of suitable laying equipment. Such an experiment is described in the techincal periodical titled: "Kertgazdasag" (Hungary) No. 4 volume 7, p. 24-28, 1975. Apparatus named FOLTERON-60 was used as a prototype in this experiment. The essential feature of that apparatus was that a wing-type subsoiler was fixed to a semi-suspended frame, and the plastic coil to be laid was arranged in a hollow rear part of the machine. The plastic irrigation pipe was guided from the large diameter fixed to the frame, to the upper part of the subsoiler, from where it passed to below the ground surface through the laying hole on the lower part of the tool.
This apparatus was not generally used in practice, because it was not possible to keep the laying equipment at a proper level and at a reliable adjustment. The plastic tape storage drum arranged at the bottom could not be controlled during operation and the traction power requirement of the apparatus was too high. Guiding the plate at the bottom resulted in further disadvantage in that only a small amount of plastic tape could be wound onto the small diameter drum, which hindered the continuity of the operation and reduced the productivity. Thus this machine was not suitable for the economical, large-scale realization of the HYDRAK process.